Hiking or being in nature is enjoyable, but exposure to poison oak causes a very itchy, blistery rash that will quickly put a damper on your fun. The leaves of this plant have a recognizable appearance if you know what to look for. If you haven’t ever been exposed to poison oak, there are ways to prevent poison oak exposure through plant identification.

Steps

Part 1

Finding Poison Oak

1

Learn about poison oak. Poison oak is similar to its close relatives poison ivy and poison sumac because they are all members of the same botanical family. The most common type of poison oak, known as western poison oak, grows most commonly along the Pacific coast in Oregon, Washington, and California. It can grow as a small shrub in open spaces or as a climbing vine in shaded forest areas.[1]

Other varieties of poison oak include Atlantic poison oak, which grows in the southeast US. This variety is much less common than the western poison oak.[2]

2

Be careful when examining the plant. A good way to avoid a poison oak rash is to never touch a plant that you think may be poison oak. In order to get close enough to the plant to identify it, use a stick or a gloved hand to examine it more closely.

If it turns out to be poison oak, make sure anything that has come into contact with the plant is washed with soap and water.

3

Look at the leaves. Poison oak, whether it is growing as a shrub or a climbing vine, has a trifoliate leaf structure. This means that the leaves grow in sets of threes off the stem. The edges of the leaves have a wavy or scalloped appearance.

Check the color. The top side of the leaves are typically a glossy green color. They can also be yellowish, reddish, or brownish depending on the health of the plant and the season. On the underside of the leaf, there is less sheen, less green, and more of a velvety appearance.[4]

5

Examine the stems. Stems tend to be a bit greyish in color, though, given the lighting in some forested areas, this can be difficult to see. The stems will also be covered in tiny hair or thorn-like structures.[5]

6

Take note of the flowers or berries. Poison oak has yellowish-green small flowers in the spring. The plant will also produce light green berries throughout the summer and into the fall.[6]

This will help you rule out other plants by noting what it doesn’t have. If it doesn’t have pointed leaves and it doesn’t have thorns, it isn’t poison oak.

7

Learn other forms of poison oak.

In the winter, it loses its leaves and looks like reddish-brown sticks (sometimes a few poking up from the ground, sometimes a big clump) with alternating stubs.

You can also find it as a thick vine climbing up a tree, sometimes (depending on the season) with small poison oak leaves coming out of it.

Part 2

Recognizing the Poison Oak Rash

1

Learn what causes the rash. Both the leaves and the stems of poison oak contain urushiol, an oily plant substance that triggers an allergic reaction in the form of the poison oak rash. Urushiol can also be found in the roots and even in the dead plant.[7]

In addition, urushiol can become airborne if the plant is burned and is easily transported from one object to another.

The rash from poison oak is not contagious in the standard sense, but if someone has the urushiol on their hands and touches another person, that second person can react as well.

All parts of the poison oak plant contain the toxin urushiol. Even when the leaves fall off in winter, the plant is not safe to touch.[8]

2

Recognize the rash. A rash from exposure to poison oak can vary depending on the person because some people are more sensitive to urushiol than others. In general, the rash will be very itchy and very red, with red bumps that may blister and ooze fluids. The rash can be streaky and patchy and can range from relatively mild to very severe.[9]

3

Wash your skin and clothes. When you are exposed to poison oak, first rinse off any exposed area with soap and warm water as soon as possible, hopefully within 30 minutes.[10] Also wash any clothing or tools that may have been exposed to the plant.[11]

4

Relieve the itching. In order to help relieve the itching of the rash, apply calamine lotion to the site. You can also apply topical steroids such as clobetasol or systemic steroids and antihistamines. Also try a cold compress or an oatmeal bath.[12]

To make an oatmeal bath, pour two cups of oatmeal into a nylon sock or stocking and tie it onto the tap so that warm bath water runs through the oatmeal. Soak in the tub or soak the affected areas for at least 30 minutes.

Keep the rash from spreading to others. Be aware that urushiol can be easily passed to another person, animal, or object. Make sure anything or anybody that may have come into contact with poison oak is carefully washed with soap and water.[14]

Most rashes will heal in five to 12 days, but the rash can last as long as a month or more.[15]

6

Seek medical help. Call emergency services if the reaction to the poison oak is severe. You should also call is you or the infected the person has trouble swallowing, breathing, or has severe swelling at the site of contact or anywhere on the body.[16]

You can use glyphosate, triclopyr or a combination of these chemicals to kill the poison oak plants. Do this at the beginning of the growing season, while the plants are still green. The plant will will drink in the chemical down to the roots. Once the plants are dead, you'll need to go back and dig them out.

I have a plant in my yard that caused a straight line of blisters along my arm. What could it be?

wikiHow Contributor

The wild parsnip can cause such blisters. If the sap of the plant touches your skin and then your skin is exposed to sunlight, blisters will form. Look up photos of blisters caused by the wild parsnip and see if yours look similar.

If a vine is in a shrub, will the shrub become poisonous even if the vine is removed?

wikiHow Contributor

The shrub itself will not be poisonous, but oil from the vine can remain on it, just like it can remain on skin and clothes. If the shrub is in a high-traffic area, like a playground or trail, you might want to prune away leaves that were in close contact.

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Tips

The best way to avoid contact with poison oak is by wearing long pants and sleeves when walking outdoors.

Dishwashing liquid is excellent for washing off the poisonous residue from poison oak, especially if it can be used right away. Bring it, along with water and paper towels if you are going on an outing where you may come in contact with the plant and identify it a moment too late.